Tutorial | Simultaneous contrast


In this journal post we look at simultaneous contrast and the subjectivity of perceptions.

As we begin to learn to paint it is usual to assume that we see things accurately as they are. However, human vision is based on context and subject to many illusions. In learning how to paint what we see, it is important that we become familiar with these illusions and know how to tackle them when they arise. Today we'll explore just one of these illusions, one that you will discover occurs time and again.

One of the most important facts to understand when we endeavour to represent what we see is that human vision is subjective. Our perception of colour is heavily affected by a colour's surroundings. One attribute of a colour that is very keenly affected by its surroundings is a colour's value. The checker shadow (above) illustrates this clearly. Squares A and B are of the same value, contrary to what we might first assume. If we connect these two tiles in one consistent value the illusion is dispelled. 

Simultaneous contrast can have a profound effect on our ability to make accurate decisions when judging colours in our painting. Overlaying on the Rembrandt image above, each of the red dots across the face is the same colour, but in the light of the cheek the colour appears significantly darker than it does placed in the dark value of the hat. A common mistake therefore is for students to exaggerate lights they see in the darks and darks they see in the lights. This mistake breaks up the unity of the whole. 

Another attribute of colour affected by simultaneous contrast is intensity. In the image above, tiles A and B and C are exactly the same: a low intensity orange. From 'A' we see that colours surrounded by more saturated colors will appear greyer. From 'B' we see that the same colour appears more saturated when surrounded by more muted colours. From 'C' we see that we can push the intensity of a colour but surrounding, in this case, the warm orange/red colour with a cool colour. This insight is very important to us when we wish to depict skin tones. A classic mistake is to depict every colour as very intense (saturated), particularly the warm the colours, which can lead to very orange figures or portraits. You can see how Rembrandt avoided making this mistake when we compare the colour on his cheek with the more saturated swatch alongside.

There are some simple things we can do to overcome the effect of simultaneous contrast once we understand how it operates: squinting, obscuring some of the details of the subject in our vision, simplifying the subject into a few simple groups of colour to establish a broad context early within the creation of our painting. The unfinished portrait by Bastien Lepage demonstrates a process which prioritises context. Lepage makes huge simplifications throughout the image to establish large masses of simplified colour. Once the context is established he moves to finishing smaller areas, as we can see with the wonderfully finished head.

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